is there a plugin that controls the out put of the sound on a track? To have it be in sync with a tempo such as half notes, quarter, eight note, 16th and so on. I think it would be a cool effect for the master output channel, I know the pioneer djm 800 dj mixer has that effect built into a tap button, was wondering if logic 7 offers something similiar, I want to be able to control this parameter via midi.

You mean lowering the output in sync ? You could do this with the "Modulation > Tremolo" plugin. 1-Insert it on your output channel. 2-Set the "Symmetry" parameter to 50 %. 3-Set "Smoothing" to 0% 4-Set "phase" to 0... if not it will create a stereo effect. 5-Set "Rate" to taste (Turn the knob left for musical values 1/4, 1/8, 1/16, etc). 6-Set "Depth" to taste. You could also do this with Side-Chaining... Tell me if that is what you were looking for!